Abstract

The genus Diaphus is taxonomically one of the most difficult in the family Myctophidae. In the Southwest Indian Ocean, at least 18 species of the genus are found but larval development is known for only two. Larvae and juveniles collected in or near the Agulhas Current provide sufficient data to describe larvae or transforming stages of three species of the genus. Postflexion and transforming specimens of D. diadematus, larvae and transforming stages of another species, either D. brachycephalus or D. richardsoni, and the complete larval development and transforming stages of D. mollis are described. The pigmentation pattern and photophore development of the larvae and juveniles of these three species, and the postanal pigmentation and presence or absence of suborbital photophores for juveniles of nine additional species, allowed them to be placed in two divergent groups of Diaphus, as suggested by previous authors.